1. Field of Invention
The field of the currently claimed embodiments of this invention relates to multichannel vestibular prosthesis and to application specific integrated circuits (ASICs) for vestibular prostheses.
2. Discussion of Related Art
In normal individuals, sensory endorgans within the labyrinth in each inner ear modulate activity on afferent fibers of each of 5 vestibular nerve branches in order to provide the central nervous system with sensation of rotational head motion and gravitoinertial linear acceleration (J. P. Carey and C. C. Della Santina, “Principles of applied vestibular physiology,”. C. W. Cummings, Ed. Elsevier, 2005). Vestibular sensory input drives compensatory reflexes that stabilize gaze and posture to maximize clarity of vision during head movements and to prevent falls. Individuals who have suffered damage to their vestibular organs, commonly due to ototoxic medications, experience disabling loss of visual acuity and balance (C. C. Della Santina, A. A. Migliaccio, R. Hayden, T. A. Melvin, G. Y. Fridman, B. Chiang, N. S. Davidovics, C. Dai, J. P. Carey, L. B. Minor, I. C. W. Anderson, H. Park, S. Lyford-Pike, and S. Tang, “Current and future management of bilateral loss of vestibular sensation—an update on the Johns Hopkins multichannel vestibular prosthesis project,” Cochlear Implants International, (in press) 2010).
Recently, interest has grown in creating vestibular prostheses that can restore lost function to severely affected patients, much as a cochlear implant restores auditory input to the deaf and severely hard of hearing. Several promising studies using a single-channel device have been reported. See the following for some examples:                W. S. Gong and D. M. Merfeld, “Prototype neural semicircular canal prosthesis using patterned electrical stimulation,” Ann Biomed Eng, vol. 28, no. 5 2000.        W. S. Gong and D. M. Merfeld, “System design and performance of a unilateral horizontal semicircular canal prosthesis,” IEEE Transactions on Biomedical Engineering, vol. 49, no. 2 2002.        D. M. Merfeld, W. S. Gong, J. Morrissey, M. Saginaw, C. Haburcakova, and R. F. Lewis, “Acclimation to chronic constant-rate peripheral stimulation provided by a vestibular prosthesis,” IEEE Transactions on Biomedical Engineering, vol. 53, no. 11 2006.        D. M. Merfeld, C. Haburcakova, W. Gong, and R. F. Lewis, “Chronic vestibulo-ocular reflexes evoked by a vestibular prosthesis,” IEEE Transactions on Biomedical Engineering, vol. 54, no. 6 2007.        W. S. Gong, C. Haburcakova, and D. M. Merfeld, “Vestibulo-Ocular Responses Evoked Via Bilateral Electrical Stimulation of the Lateral Semicircular Canals,” IEEE Transactions on Biomedical Engineering, vol. 55, no. 11 2008.        R. F. Lewis, D. M. Merfeld, and W. S. Gong, “Cross-axis vestibular adaptation produced by patterned electrical stimulation,” Neurology, vol. 56, no. 8 2001.        R. F. Lewis, W. S. Gong, M. Ramsey, L. Minor, R. Boyle, and D. M. Merfeld, “Vestibular adaptation studied with a prosthetic semicircular canal,” Journal of Vestibular Research-Equilibrium & Orientation, vol. 12, no. 2-3 2002.A Stimulator ASIC Featuring Versatile Management for Vestibular Prostheses        Dai Jiang, Member, IEEE, Andreas Demosthenous, Senior Member, IEEE, Timothy A. Perkins, Xiao Liu, Member, IEEE, and Nick Donaldson, IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, VOL. 5, NO. 2, April 2011        
Because the normal vestibular labyrinth senses head movement in all 3 directions, we have extended this approach to a multichannel vestibular prosthesis (MVP) that modulates activity of surviving vestibular afferent fibers in 3 ampullary nerves that normally encode each of 3 components of head rotation. See the following:                C. C. Della Santina, A. A. Migliaccio, and A. H. Patel, “Electrical stimulation to restore vestibular function—development of a 3-D vestibular prosthesis,” Shanghai, China: 2005.        C. C. Della Santina, A. A. Migliaccio, and A. H. Patel, “A multichannel semicircular canal neural prosthesis using electrical stimulation to restore 3-D vestibular sensation,” IEEE Transactions on Biomedical Engineering, vol. 54, no. 6 2007.        G. Y. Fridman, N. Davidovics, C. Dai, and C. C. Della Santina, “Multichannel Vestibular Prosthesis Stabilizes Eyes For Head Rotation About Any Axis,” Journal of the Association for Research in Otolaryngology, vol. Submitted 2009, 2009.        B. Chiang, G. Y. Fridman, and C. C. Della Santina, “Enhancements to the Johns Hopkins Multi-Channel Vestibular Prosthesis Yield Reduced Size, Extended Battery Life, Current Steering and Wireless Control,” presented at Association for Research in Otolaryngology Abst. 867, Baltimore, Md. 2009.        N. S. Davidovics, G. Y. Fridman, B. Chiang, C. C. Della Santina, “Effects of biphasic current pulse frequency, amplitude, duration and interphase gap on eye movement responses to prosthetic electrical stimulation of the vestibular nerve,” IEEE Trans Neural Syst Rehabil Eng. 2011 February; 19(1):84-94.Previous iterations of our MVP design have successfully restored vestibular reflexes in animal experiments, providing strong support for the promise of MVPs improving quality of life for vestibular-deficient individuals. However, to date, there still remain no fully functional, fully implantable vestibular prostheses. There thus remains a need for improved vestibular prostheses.        